On 08/05/2015 02:20 AM, Michel Dänzer wrote:
> From: Michel Dänzer <[email protected]>
>
> Fixes a bunch of random (mostly tessellation related) piglit failures
> since commit 7ac946e5 ("glsl: Add constuctors for the common cases of
> glsl_struct_field").
I was going to look at this yesterday, but I didn't get to it. :(
That said, this is not the patch that I would have anticipated. I
thought these paths should have used the default constructor, but I
think your change is correct. It took a bit of research to convince
myself. He's my thinking (and some of this should end up in the commit
message)...
There is apparently a subtle difference in C++ between
F f;
and
F f();
The former will use the default constructor. If there is no default
constructor specified, the compiler provides one that simply invokes the
default constructor for each field. For built-in basic types, the
default constructor does nothing. The later will, according to
http://stackoverflow.com/questions/2417065/does-the-default-constructor-initialize-built-in-types)
perform value-initialization of the type. For built-in types this means
initializing to zero.
The per_vertex_accumulator constructor is:
per_vertex_accumulator::per_vertex_accumulator()
: fields(),
num_fields(0)
{
}
This is the second form of constructor, so the glsl_struct_field
objects were previously zero initialized. With the addition of an empty
default constructor in commit 7ac946e5, per_vertex_accumulator::fields
receive no initialization.
> Signed-off-by: Michel Dänzer <[email protected]>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91544
Reviewed-by: Ian Romanick <[email protected]>
> ---
> src/glsl/builtin_variables.cpp | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/src/glsl/builtin_variables.cpp b/src/glsl/builtin_variables.cpp
> index 0ff3a3f..b8ad2c9 100644
> --- a/src/glsl/builtin_variables.cpp
> +++ b/src/glsl/builtin_variables.cpp
> @@ -322,6 +322,7 @@ per_vertex_accumulator::add_field(int slot, const
> glsl_type *type,
> this->fields[this->num_fields].interpolation = INTERP_QUALIFIER_NONE;
> this->fields[this->num_fields].centroid = 0;
> this->fields[this->num_fields].sample = 0;
> + this->fields[this->num_fields].patch = 0;
> this->num_fields++;
> }
>
> @@ -1159,6 +1160,7 @@ builtin_variable_generator::generate_varyings()
> var->data.interpolation = fields[i].interpolation;
> var->data.centroid = fields[i].centroid;
> var->data.sample = fields[i].sample;
> + var->data.patch = fields[i].patch;
> var->init_interface_type(per_vertex_out_type);
> }
> }
>
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